- Select the weight, creatinine, and height units to match your records. Switching a unit clears that field.
- Enter age, select sex, and enter the actual body weight.
- Enter the steady-state serum creatinine — not a value drawn during acute illness or AKI.
- Optionally enter height to compute Devine ideal body weight (IBW) and adjusted body weight.
- Choose the weight to use in the formula — actual, ideal, or adjusted. In obesity, ideal or adjusted weight is preferred.
- The result shows CrCl in mL/min, the weight used, the IBW, the dosing band, and a recommended action.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use the Cockcroft-Gault equation to estimate creatinine clearance (CrCl) for renal drug dosing. Many drug labels — and most foundational pharmacokinetic studies — express renal dose thresholds in terms of Cockcroft-Gault CrCl in mL/min, not in eGFR. For any renally cleared or narrow-therapeutic-index agent, the prescribing information's renal-dosing table was usually built on this equation, so matching the label means using this calculator.
Appropriate population
Adults (≥18 years) with a stable, steady-state serum creatinine who are being dosed on a renally-cleared drug whose label specifies creatinine clearance. The optional height field enables Devine ideal body weight (IBW) and adjusted body weight, which are preferred over actual weight at the extremes of body habitus (obesity or very low weight).
When NOT to rely on it
Do not use during acute kidney injury or any non-steady state — Cockcroft-Gault assumes stable creatinine. It is not the CKD-staging tool: for staging and the GFR category, use CKD-EPI eGFR. The result is unindexed (mL/min), not normalized to body-surface area, so do not compare it directly to an eGFR in mL/min/1.73 m². Accuracy degrades at extremes of muscle mass, in amputees, and in unstable renal function. Always confirm against the specific drug's prescribing information.
Pearls & Pitfalls
Match the label's equation
When a drug label specifies a dose by creatinine clearance, use Cockcroft-Gault — not eGFR. The label's thresholds were almost always derived with this equation, so reproducing it keeps the patient in the dosing band the manufacturer validated.
Choose the right weight
Use actual weight for normal-range patients, but switch to ideal or adjusted body weight in obesity, and consider ideal weight in low-weight patients. Using actual weight in obesity overestimates clearance and can push a dose too high; enter height to enable the Devine options.
Pitfalls
(1) Do not use during AKI or any unstable creatinine — the estimate assumes steady state. (2) The result is unindexed (mL/min); do not equate it with an eGFR in mL/min/1.73 m². (3) Accuracy falls at extremes of muscle mass and in amputees. (4) This is a dosing tool, not a CKD-staging tool — use CKD-EPI eGFR for staging. Always confirm against the specific drug's prescribing information.
Why Use It
Substituting eGFR for Cockcroft-Gault CrCl can move a patient into the wrong dosing band for drugs such as direct oral anticoagulants, certain antimicrobials, and chemotherapeutics — risking under-dosing (treatment failure) or over-dosing (toxicity). Because the original safety and efficacy thresholds for many agents were defined using Cockcroft-Gault, reproducing the equation the label intended preserves the validated dosing logic. Using ideal or adjusted body weight where appropriate further protects obese and underweight patients from systematic over- or under-estimation of clearance.
Cockcroft-Gault Creatinine Clearance (CrCl) Calculator — for Drug Dosing
Enter age, sex, weight, and serum creatinine to estimate CrCl for drug dosing and see the dosing band. Add height to enable ideal/adjusted body weight for patients at the extremes of body habitus.
⚕ Cockcroft-Gault: CrCl = [(140 − age) × weight(kg) × (0.85 if female)] / (72 × SCr mg/dL). Devine IBW: men 50 + 2.3×(height in − 60); women 45.5 + 2.3×(height in − 60); Adjusted BW = IBW + 0.4×(actual − IBW). Estimates renal clearance for DRUG DOSING only — it is not the CKD-staging eGFR and requires physician confirmation. At extremes of body habitus (obesity or very low weight), use ideal or adjusted body weight. Source: Cockcroft DW, Gault MH. Nephron. 1976;16(1):31–41.
Next Steps
Use the result to support — not replace — clinical judgment.
- Interpret the value against the targets shown in the calculator and the Evidence section below, in the context of the full clinical picture.
- Trend serial measurements rather than acting on a single result; confirm abnormal or unexpected values before changing management.
- Apply the relevant KDIGO / specialty-guideline threshold and document the indication.
- Escalate or refer to nephrology when results are out of range, rapidly changing, or discordant with the clinical picture — and discuss the implications with the patient.
Evidence & References
Formula & Equations
| Quantity | Equation |
|---|---|
| Creatinine clearance (mL/min) | [(140 − age) × weight in kg × (0.85 if female)] ÷ (72 × SCr in mg/dL) |
| Ideal body weight — men (Devine) | 50 + 2.3 × (height in inches − 60) |
| Ideal body weight — women (Devine) | 45.5 + 2.3 × (height in inches − 60) |
| Adjusted body weight | IBW + 0.4 × (actual weight − IBW) |
| SI conversion | SCr (mg/dL) = SCr (µmol/L) ÷ 88.4; weight (kg) = lb ÷ 2.2046; height (in) = cm ÷ 2.54 |
Dosing bands
| CrCl (mL/min) | Dosing implication |
|---|---|
| ≥ 50 | Standard dosing — verify the per-drug renal threshold |
| 30–49 | Many renally-cleared drugs need dose reduction or interval extension |
| 15–29 | Significant reduction; avoid nephrotoxins where possible |
| < 15 | Minimal renal clearance; many agents contraindicated — use specialist/dialysis dosing |
Cockcroft-Gault CrCl is unindexed (mL/min) and is not normalized to 1.73 m² body-surface area. These bands are general; always check each drug's prescribing information for its specific renal thresholds.
Evidence & References
The Cockcroft-Gault equation was published in 1976 and remains the reference method for renal drug dosing because the pharmacokinetic dose-adjustment studies and regulatory labels for many drugs were built on it. The Devine formulas (1974) provide the ideal body weight used for dosing in obesity. KDIGO and prescribing references note that creatinine-based clearance and indexed eGFR are not interchangeable for dosing decisions.
- Cockcroft DW, Gault MH. Prediction of Creatinine Clearance from Serum Creatinine. Nephron. 1976;16(1):31–41.
- Devine BJ. Gentamicin Therapy. Drug Intell Clin Pharm. 1974;8(11):650–655.
- Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314.
